Which sleep stage increases in duration with each sleep cycle? Stage 2 Stage 3 Stage 4 Rapid – eye – movement ( REM ) stage

Answer

REM Sleep Duration Increases with Each Sleep Cycle

🛌 Which Sleep Stage Increases in Duration with Each Sleep Cycle?

🔍 Answer: Rapid Eye Movement (REM) Stage

✅ Correct Answer: Rapid-eye-movement (REM) stage

During the course of a full night’s sleep, humans cycle through various stages of sleep — Stage 1, Stage 2, Stage 3, Stage 4 (sometimes grouped as deep sleep), and REM sleep. These cycles repeat approximately every 90 minutes. However, one stage in particular becomes longer and more dominant in the later part of the night: REM sleep.

📘 Breakdown of Sleep Stages

Stage 1: Lightest sleep, transition from wakefulness.
Stage 2: Light sleep with decreased body temperature and heart rate.
Stage 3 & 4: Deep sleep stages (also called slow-wave sleep).
REM Sleep: Dreaming stage, brain highly active, body is paralyzed.

      🧠 REM sleep increases in length with each cycle, while deep sleep (Stage 3/4) decreases as the night progresses.
    

🧠 Why REM Sleep is Important

REM sleep plays a critical role in:

Memory consolidation
Emotional processing
Learning and cognition
Brain development (especially in infants)

🌙 Fun Fact: The first REM period of the night might last only 10 minutes. By the final cycle, it can last up to an hour!

🚫 Explanation of Incorrect Options

Stage 2:
❌ While it makes up a large portion of total sleep, its duration stays relatively stable across cycles.

Stage 3:
❌ This deep sleep stage actually decreases as the night progresses.

Stage 4:
❌ Also part of deep sleep, it’s more prominent in the earlier cycles and tapers off later.

🌐 Summary

✅ Stage that increases in duration: REM Sleep
🧠 Functions: Memory, learning, emotional regulation, dreaming
⏰ Cycle change: From ~10 minutes early night to ~1 hour near waking

For a healthy mind and body, consistent and complete sleep cycles — including adequate REM sleep — are essential.

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